When it was developed the K&N Filtercharger was an air filtration breakthrough and it still has the edge today...

Simple, economical high-performance add-on improves acceleration and adds about 1 to 4 horsepower to your engine. Virtually unrestricted airflow with exceptional filtration built to last the life of an engine. Made of 4 to 6 sheets of high-flow cotton gauze layered between 2 aluminum wire mesh sheets that are pleated and oiled to enhance filtering and overall performance. Washable, reusable, and environmentally-friendly. Drive up to 50,000 miles before filter cleaning is required (depends on driving conditions)